title: The effect of degenerative morphological changes of the intervertebral disc on the lumbar spine biomechanics: a poroelastic finite element investigation.
abstract: Intervertebral disc degeneration involves changes in the spinal anatomical structures. The mechanical relevance of the following changes was investigated: disc height, endplate sclerosis, disc water content, permeability and depressurisation. A poroelastic nonlinear finite element model of the L4-L5 human spine segments was employed. Loads represented a daily cycle (500 N compression combined with flexion-extension motion for 16 h followed by 200 N compression for 8 h). In non-degenerative conditions, the model predicted a diurnal axial displacement of 1.32 mm and a peak intradiscal pressure of 0.47 MPa. Axial displacement, facet force and range of motion in flexion-extension are decreased by decreasing disc height. By decreasing the initial water content, axial displacement, facet force and fluid loss were all reduced. Endplate sclerosis did not have a significant influence on the calculated results. Depressurisation determined an increase of the disc effective stress, possibly inducing failure. Degenerative instability was not calculated in any simulations.
authors.affiliation: Institute of Orthopaedic Research and Biomechanics, University of Ulm , Helmholtzstrasse, Germany. fabio.galbusera@uni-ulm.de
authors.forename: Fabio
authors.initials: F
authors.lastname: Galbusera
authors.forename: Hendrik
authors.initials: H
authors.lastname: Schmidt
authors.forename: Cornelia
authors.initials: C
authors.lastname: Neidlinger-Wilke
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Wilke
mesh_terms: D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000473:pathology* / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000473:pathology* / Q000503:physiopathology